100/180 mm PAPERLESS GRAPHIC RECORDER: USER GUIDE
HA028910
Issue 13 Sep 16
User Guide
Page 120
4.3.11 FUNCTION (Cont.)
SATURATED STEAM MASS FLOW
Note: The overall accuracy of a fl ow measurement installation depends on a number of factors
outside the control of the recorder manufacturer. For this reason, the recorder manufacturer takes
no responsibility for the accuracy of the results obtained using the mass fl ow equations imple-
mented in the maths pack.
The equation solved is:
where, QM
t
= Mass fl ow (in kg/sec), at time ‘t’ (Note 1)
Flow
t
= Measured fl ow in m3/sec. at time ‘t’ (Note 1)
V
LT
= Volume of liquid per kg of steam (m
3
/kg) at temperature T ˚C
∆VT = V
VT
- V
LT
, where V
VT
is the volume of vapour per kg of steam at temperature T ˚C
d = Dryness factor between 0 (no vapour) and 100 (no liquid)
V
LT
and ∆V
T
are available from published tables (note 2), but the recorder user need only enter ‘values’ for
measured fl ow and either the temperature or the pressure of the steam. These ‘values’ can be constants,
input channels or maths channels. Figure 4.3.11h and accompanying parameter descriptions give full
details.
QM
t
!
Flow
t
V
LT
# &
V
T
d
100
. /
Function
Flow
Use
Temperature
Dryness
Units
Maths Number
Value
Units
Apply Discard
%
Saturated Steam Mass Flow
Channel 1
0
Units
1) Math 1
123.4567
Temperature
Channel 2
Figure 4.3.11h Typical Saturated Steam Mass Flow confi guration page
PARAMETERS
Flow
Select ‘Constant’ or the number of the channel supplying the measured fl ow rate. If
‘Constant’ selected, a further ‘box’ allows the value for the constant to be entered.
Use
Allows the user to select Temperature (˚C) or Pressure (MPa) for the calculation.
Temperature
Appears only if Use = Temperature. Select ‘Constant’ or the number of the channel
supplying the steam temperature. If ‘Constant’ is selected, a further ‘box’ allows a
value for the constant to be entered.
Pressure
Appears only if Use = Pressure. Select ‘Constant’ or the number of the channel sup-
plying the steam pressure. If ‘Constant’ is selected, a further ‘box’ allows a value for
the constant to be entered.
Table 4.3.11b, below, gives multipliers for converting some common pressure units
to MPa. More details may be found at websites http://www.ex.ac.uk/trol/scol/
ccpress.htm and http://www.onlineconversion.com/pressure.htm, amongst others.
Dryness
Enter a value between 0 and 100 to represent the dryness of the steam. 0 = no va-
pour; 100 = no liquid.
Notes:
1 The units of kg/sec and m
3
/sec are used above for simplicity. In fact any time unit can be used.
For example if the measured fl ow is in m3/hour, then the Mass fl ow will be in kg/hour.
2. ASME Steam tables 1999, from IAPWF IF97.
